absolute.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2018 John Wellbelove
 
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#ifndef ETL_ABSOLUTE_INCLUDED
#define ETL_ABSOLUTE_INCLUDED
 
#include "platform.h"
#include "error_handler.h"
#include "integral_limits.h"
#include "type_traits.h"
 
namespace etl
{
  namespace private_absolute
  {
    //*************************************************************************
    // Non-constexpr function that is never called for valid inputs.
    // If reached during constant evaluation, the compiler emits an error
    // because it's not constexpr.
    // At runtime, triggers the ETL assert handler.
    //*************************************************************************
    template <typename T>
    inline T signed_min_error()
    {
      ETL_ASSERT_FAIL(ETL_ERROR_GENERIC("absolute value of minimum signed integer is undefined"));
      return T(0);
    }
  } // namespace private_absolute
 
  //***************************************************************************
  // For signed types.
  //***************************************************************************
  template <typename T>
  ETL_NODISCARD ETL_CONSTEXPR typename etl::enable_if< etl::is_signed<T>::value && etl::is_integral<T>::value, T>::type absolute(T value)
  {
    return (value == etl::integral_limits<T>::min) ? etl::private_absolute::signed_min_error<T>() : static_cast<T>((value < T(0)) ? -value : value);
  }
 
  template <typename T>
  ETL_NODISCARD ETL_CONSTEXPR typename etl::enable_if< etl::is_signed<T>::value && !etl::is_integral<T>::value, T>::type absolute(T value)
    ETL_NOEXCEPT
  {
    return (value < T(0)) ? -value : value;
  }
 
  //***************************************************************************
  // For unsigned types.
  //***************************************************************************
  template <typename T>
  ETL_NODISCARD ETL_CONSTEXPR typename etl::enable_if<etl::is_unsigned<T>::value, T>::type absolute(T value) ETL_NOEXCEPT
  {
    return value;
  }
 
  //***************************************************************************
  // For signed types.
  // Returns the result as the unsigned type.
  //***************************************************************************
  template <typename T>
  ETL_NODISCARD ETL_CONSTEXPR typename etl::enable_if<etl::is_signed<T>::value, typename etl::make_unsigned<T>::type>::type absolute_unsigned(T value)
    ETL_NOEXCEPT
  {
    typedef typename etl::make_unsigned<T>::type TReturn;
 
    return (value == etl::integral_limits<T>::min) ? (etl::integral_limits<TReturn>::max / 2U) + 1U
           : (value < T(0))                        ? TReturn(-value)
                                                   : TReturn(value);
  }
 
  //***************************************************************************
  // For unsigned types.
  // Returns the result as the unsigned type.
  //***************************************************************************
  template <typename T>
  ETL_NODISCARD ETL_CONSTEXPR typename etl::enable_if<etl::is_unsigned<T>::value, T>::type absolute_unsigned(T value) ETL_NOEXCEPT
  {
    return etl::absolute(value);
  }
} // namespace etl
 
#endif